By controlling for a variety of social and biological factors (such as neighborhood socioeconomic status, marital status of mother, residential mobility, family structure changes, and mental health), and the use of a strong statistical design—propensity score matching with a large population-based dataset—this study aims to determine whether teenage pregnancy is more strongly predicted by having an older sister who had a teenage pregnancy or by having a mother who bore her first child before age 20.
The setting of this study, Manitoba, is generally representative of Canada as a whole, ranking in the middle for several health and education indicators [12, 13].
In this study, teenage pregnancies are defined as those between the ages of 14 and 19; pregnancies prior to age 14 were excluded due to low numbers and for comparability to other studies.
For this reason, families in which at least one sister had a pregnancy before age 14 were removed (34 families).
Given approximately 16,000 births annually, follow-up (about 74 % over 20 years) is comparable to that in the largest cohort studies based on primary data .
Previous research using similar data shows the results are not biased by individuals leaving the province or dying.
This study used linkable administrative databases housed at the Manitoba Centre for Health Policy (MCHP).
The original cohort consisted of 17,115 women born in Manitoba between April 1, 1979 and March 31, 1994, who stayed in the province until at least their 20 birthday, had at least one older sister, and had no missing values on key variables.
Risk factors for teenage pregnancy are linked to many factors, including a family history of teenage pregnancy.
This research examines whether a mother’s teenage childbearing or an older sister’s teenage pregnancy more strongly predicts teenage pregnancy.